Veterinary Science - Research Publications

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    Pilot field trial of the EG95 vaccine against ovine cystic echinococcosis in Rio Negro, Argentina: Early impact and preliminary data
    Larrieu, E ; Herrero, E ; Mujica, G ; Labanchi, JL ; Araya, D ; Grizmado, C ; Calabro, A ; Talmon, G ; Ruesta, G ; Perez, A ; Gatti, A ; Santillan, G ; Cabrera, M ; Arezzo, M ; Seleiman, M ; Cavagion, L ; Cachau, MG ; Alvarez Rojas, CA ; Gino, L ; Gauci, CG ; Heath, DD ; Lamberti, R ; Lightowlers, MW (ELSEVIER, 2013-08-01)
    Cystic echinococcosis is endemic in the Rio Negro province of Argentina. After 30 years of control using praziquantel in dogs the transmission rate to humans and sheep has decreased significantly, however transmission persists. The objective of the study is to assess the impact of the inclusion of the EG95 vaccine for sheep in the control programme, including analysis of the vaccine's operative feasibility in field conditions. The vaccine was applied in an area comprising four communities of native people including 79 farms with 3146 lambs and 311 dogs in total. Seventy one farms were designated as control areas where no vaccinations were undertaken while vaccinations of lambs undertaken on 91 farms. Lambs received two vaccinations with the EG95 vaccine followed by a single booster injection when the animals were 1-1.5 years of age. Farm locations were defined using GPS coordinates for the houses. Evidence for Echinococcus granulosus transmission was monitored by coproantigen ELISA on samples of dog faeces, by E. granulosus-specific PCR using soil samples, and anti-E. granulosus antibody assessments in sera from 2 to 4 teeth lambs, purgation of dogs to detect E. granulosus worms and necropsy on adult sheep. Before the vaccine was introduced, 26.2% of sheep with 2-4 teeth were positive using ELISA/WB, the prevalence decreased to 7.8% at the third year following use of the vaccine. Necropsy of animals older than 6 years (not vaccinated) showed that 66.1% of animals were infected with E. granulosus. In dogs, 4% was found positive for E. granulosus using arecoline purgation and 24.7% of the farms were infected using coproELISA/WB. During the first year of vaccination 2721 lambs received the first vaccine dose and 2448 received a booster. In the second year 2138 lambs were initially vaccinated and 1745 received a booster, and 1308 animals received the third dose. During the third year 1110 lambs received the first dose from which 539 received a booster and 723 animals received the third dose. An analysis of advantages and limitations of the diagnostic techniques used and the ability of the geospatial analysis to detect risk area are included. Based in the immunodiagnostic techniques, the EG95 vaccine has been able to prevent the infection in animals up to 3 years old. Also, the difficulties in the field for the correct vaccine administration and the social features and habits that may impact on echinococcosis control are included in the analysis.
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    Antigenic differences between the EG95-related proteins from Echinococcus granulosus G1 and G6 genotypes: implications for vaccination
    Rojas, CAA ; Gauci, CG ; Lightowlers, MW (WILEY-BLACKWELL, 2013-02-01)
    Cystic echinococcosis caused by Echinococcus granulosus remains an important and neglected issue in public health. The study of the likely efficacy of the currently available EG95 vaccine against other genotypes of the parasite is important to improve the vaccine as a potential tool to be used in control programmes. The recombinant vaccine EG95-1G1 was developed based on the G1 genotype of E. granulosus. Characterization of the eg95 gene family in the G6 genotype by genomic DNA cloning previously produced the first unequivocal information about the composition of the gene family in a different genotype. The information was used in this study to predict and express two EG95-related proteins from the G6 genotype as recombinants, for assessment of their capacity to bind antibodies raised in sheep vaccinated with the EG95-1G1 vaccine. The proteins (EG95-1G6 and EG95-5G6) from the G6 genotype of E. granulosus were unable to bind all the antibodies raised by sheep vaccinated with EG95-1G1. Differences in the amino acid sequence of EG95-related proteins from G6 and likely the differences in the encoded FnIII domain may be responsible for changes in the conformation of these epitopes.